Just google them. I myself haven't gone through them but I suppose these links on amazon to be of the same books because they have same ISBN numbers.
Absolute Beginner's Guide to C, Second Edition
Programming in C, Third Edition
How Computers Work, Ninth Edition
Henry S. Warren Jr.
Absolute Beginner’s Guide to C, Second Edition by Greg Perry
Programming in C, Third Edition by Stephen Kochan
The current versions (Fall 2015) of the lecture videos are available on youtube at the following link: https://www.youtube.com/playlist?list=PLhQjrBD2T383Xfn0zECHrOTpfOSlptPAB
However I don't know if those match the pset(s), etc. of what's currently available on the edX CS50 site.
Is the Hacker's Delight book worth having?
I have not read the book, but if your goal is indeed to "learn as much as possible", it's probably worth having. I'm sure you can learn something from it.
How can I use it to be a better coder within CS50? Or is it something I should read after I complete CS50?
The syllabus lists Hacker's Delight under ...